Elongated electrical articles, such as varistors, capacitors and diodes, of the types known as axially leaded devices, are currently mass produced in high speed production lines. Typically, these articles have two wire-like leads extending in longitudinally opposite directions from a central, generally cylindrical, body portion. The leads of these axially leaded devices are quite susceptible to being bent or deformed in the course of manufacture of the respective articles.
However, it is advantageous to have the leads of axially leaded devices nearly straight for further processing involving mass handling techniques. For example, axially leaded diodes typically are sorted and tested while they are being carried in a parallel array on a conveyor or wheel. Furthermore, since labor saving machinery is used to automatically insert such devices into printed circuit boards used in computers, test sets, and similar equipment, it is important that the leads of such devices be nearly collinear for end use. Otherwise, the automatic insertion machinery can fail to properly manipulate the devices.
Various machines are commercially available to straighten bent leads of axially leaded devices. Moreover, these machines do an effective job of straightening such bent leads, especially at medium to low rates of production. It has therefore become customary for manufacturers to run all the devices through lead straightening as a preventative measure after the devices are assembled and before such devices are further processed.
It has been recognized, however, that typically only a small percentage of the assembled devices have leads which are unacceptably bent. Thus, it has been customary to treat all the devices for a problem which exists in only a few such devices. This is a problem in that the treatment is costly and is known to ruin some good devices, especially at the high rates of production required in the industry today.
It would be far better, after the devices are assembled, to detect the devices which are defective because of bent leads and to separate such defective devices from good devices having straight leads. The large majority of good devices could then be processed without the expense of lead straightening and without the risk to such good devices.
Various efforts have heretofore been made to visually detect bent leads and to manually remove bent leaded devices from a flow of axially leaded devices in a production line. However, these efforts have proven to be rather costly and are generally effective only when the leads are excessively bent.
The presently known attempts to mechanically solve the problem of bent leads have been associated with an individual process such as the sorting or the testing of devices. For example, drums which are used to transport and to test axially leaded devices have employed grooves or slots on the periphery thereof which are purposely made very shallow. Bent leaded devices cannot readily become seated in such shallow grooves, so generally only straight leaded devices are picked up by the drum.
As another example, U.S. Pat. No. 3,581,890 to D. D. DeMuzio et al. discloses an indexable drum for testing and sorting axially leaded diodes. A pair of cams with curved ends are provided adjacent to either side of the drum, the curved ends being positioned to engage leads which are excessively bent. After bent leads are engaged, the diodes having such leads are deflected off the drum. The diodes are therefore removed if their leads are bent but the described apparatus has been found not to be readily adaptable to high speed production.